Single oral dose pharmacokinetics and comparative bioavailability of danazol in humans

A comparative bioavailability study was conducted with two capsule formulations of danazol (200 mg) in 16 healthy adult male volunteers. Fasting subjects received single doses (400 mg) of each formulation on separate occasions 1 week apart. Blood samples were drawn at specified times up to 32 h after the dose and danazol concentrations in plasma were determined by a specific and sensitive HPLC method. The results for one subject were excluded as outlier values. The data from the other 15 subjects showed small differences, which did not achieve statistical significance between the formulations with respect to Cmax, Tpeak and AUC0-infinity. The mean elimination half-life for danazol was 9.44 +/- SD 2.74 h and the mean apparent total body clearance was 710 +/- SD 2161 h-1. These data differed from previously published results, probably as a result of the more sensitive and specific assay method used in the present work. It is likely that a high proportion of the oral dose of danazol is eliminated by presystemic metabolism.